I-Delta1^ext-myc enhanced engraftment of human CD45⁺ or CD3⁺ T cells in the thymus of NOD/SCID β2m^–/– mice. We transplanted 4.7 × 10³ CD34⁺CD38^– cells or all the progeny of 4.7 × 10³ CD34⁺CD38^– cells cultured for 16, 23, or 29 days with 5GF, I-Delta1^ext-myc, and CH-296 into NOD/SCID β2m^–/– mice, and the thymus was harvested after 9 weeks. (a) Total numbers of human CD45⁺ and CD45⁺CD3⁺ cells in thymus were assessed. (b) The proportion of cells expressing CD45 in thymic cells (left panel), CD3 in thymic engrafted CD45⁺ cells (middle panel), and CD4 and/or CD8 in thymic engrafted CD3⁺ cells (right panel) are shown. Data are representative of three independent experiments.